Varying upload speeds to a server on a network

Hello - I'm trying to figure out why I'm seeing extreemely slow data upload transmission speeds from some of the workstations on our network, while other computers of the same make, and same NIC card, are uploading very fast.  The way it was discovered was through attempting Ghost backups, and some finished in an hour, while others took a day.  So I used a LAN Speed Test tool to run some testing, and saw that on the machines that were very fast, they were WRITING data at speeds of 30-40mbps, and the slow ones were under 1mbps (but reading very fast).  The machines that were tested are all connected at 100MBPS on the NIC card, and going through the same Cisco Catalyst 10/100 switch stack, and all were writing to the same drive on the same server, which has a Gigabit card in it.  So - what could cause the varying write performance?

Thanks for your help
Damian_GardnerAsked:
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giltjrConnect With a Mentor Commented:
No a duplex mismatch would not effect both sides.  It would only affect the speed going to the device that thinks the connection is half duplex.
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giltjrCommented:
Typically this is caused by a duplex mismatch.  I would verify that the NIC configuration on  PC's that are having the problem match that on the switch.

Both side should either be auto speed/auto duplex (preferred) or fixed 100./full.
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Damian_GardnerAuthor Commented:
ok - I'll check that.  So - a duplex mismatch wouldn't equally affect the read AND write speeds then?

thanks
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Damian_GardnerAuthor Commented:
I'm checking the switch ports, and in general it looks like they're all set to the same as this one port here:

interface FastEthernet2/0/42
 switchport access vlan 2    
 switchport mode access      
 speed 100                  
 duplex full                
 spanning-tree portfast      

Now - I haven't identified the exact ports in question yet, but that's what I'm noticing so far..
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Damian_GardnerAuthor Commented:
Well - I changed the "speed/duplex" setting on one of the workstations to "100/Full", and did a speedtest - and instead of .58mbps, the write speed is now about 40mbps.  That may have done it!  I'm going to try anotgher backup test to see how it goes, and report the results.

thanks
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Damian_GardnerAuthor Commented:
thanks - it's working great now.  thanks for your help.
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